Testing
Make sure you fully test your components before you publish. This saves a lot of headaches on everyone's part.
Make sure you test every platform, not just web. When you press "Preview" in the editor, you are viewing the "Web" version of your component. If you didn't use any external libraries, or if your library is a React Native library that's React Native Web compatible, this may be all you need to do; however, if you used a React-specific library, or have separate libraries for React and React Native, you must test on mobile as well.
See Testing for detailed instructions on how to test for each platform, and see Making Your Component Work Across All Platforms for an explanation of how to make your component compatible on web, iOS, and Android.